Neuropeptide Y (NPY) is a 36 amino acid neuropeptide that is widely distributed in the central and peripheral nervous systems. NPY is a member of the pancreatic polypeptide family that also includes peptide YY and pancreatic polypeptide (Wahlestedt, C., and Reis, D., Ann. Rev. Toxicol., 32, 309, 1993). NPY elicits its physiological effects by activation of at least six receptor subtypes designated Y1, Y2, Y3, Y4, Y5 and Y6 (Gehlert, D., Proc. Soc. Exp. Biol. Med., 218, 7, 1998; Michel, M. et al., Pharmacol. Rev., 50, 143, 1998). Central administration of NPY to animals causes dramatically increased food intake and decreased energy expenditure (Stanley, B. and Leibowitz, S., Proc. Natl. Acad. Sci. USA 82: 3940, 1985; Billington et al., Am J. Physiol., 260, R321, 1991). These effects are believed to be mediated at least in part by activation of the NPY Y5 receptor subtype. The isolation and characterization of the NPY Y5 receptor subtype has been reported (Gerald, C. et al., Nature, 1996, 382, 168; Gerald, C. et al. WO 96/16542). Additionally, it has been reported that activation of the NPY Y5 receptor by administration of the Y5—selective agonist [D-Trp32]NPY to rats stimulates feeding and decreases energy expenditure (Gerald, C. et al., Nature, 1996, 382, 168; Hwa, J. et al., Am. J. Physiol., 277 (46), R1428, 1999).
Published PCT patent application WO 00/27845 describes a class of compounds, characterized therein as spiro-indolines, said to be selective neuropeptide Y Y5 receptor antagonists and useful for the treatment of obesity and the complications associated therewith. Known urea derivatives indicated as possessing therapeutic activity are described in U.S. Pat. No. 4,623,662 (antiatherosclerotic agents) and U.S. Pat. No. 4,405,644 (treatment of lipometabolism). Provisional application, U.S. Ser. No. 60/232,255 describes a class of substituted urea neuropeptide Y Y5 receptor antagonists.